An example of the conventional information sharing system is described in JP-2005-222552A. As shown in FIG. 15, the conventional information sharing system includes a plurality of units, among which data and management conditions thereof are transmitted and received.
The conventional information sharing system operates as follows. In order to share data between two of the units, for example, between an office PC 51 and a unit 52, or to synchronize data between these units, one of the units, for example, office PC 51 transmits the data and the management conditions thereof to unit 52. Unit 52 that received the data automatically transmits the received data further to a home PC 53. The user can set whether or not the user permits exchange of data automatically at this state between the units which transmit and receive data therebetween. Thus, the user can limit the range of data to be shared, to control the sharing of the data.
An example of a personal information management system is described in JP-2002-269092A. In the system described in this publication, an e-market provider registers in the database of the member management system the information (opening policy), which controls access to the information, for each information class of the member information, and determines the owner (e-market provider, ASP provider, ASP, ASP user) of the member information for the each information class. Each owner registers in the database of the member management system the information (opening rule) which controls access to the member information managed and owned by the each owner. Upon request of update or reference of the member information, permission or denial of the update or reference is judged with reference to the opening policy and opening rule.
Another example of the personal management system is described in JP-2004-5583A. In the system described in the publication, policy information that describes the handling criteria of user's personal information acquired from a client and preference information that defines contents of the personal information provided from the client to a server depending on the policy information are registered in association with each other. In order to assure that the policy information is not changed without a consent of the user, the server compares preference information and policy information at present against the preference information and policy information, respectively, that are registered.
Generally, a user provides user's personal information to a provider after the user consents to the privacy policy (handling policy of the personal information) that the provider offers. A plurality of providers respectively manage the user's personal information, and are allowed to provide the personal information to another provider so long as the user consents. In this way, it is possible to transfer the personal information among the plurality of providers to share the personal information therebetween.
There may be a case where a user desires change of the privacy policy. For example, it is probable that a user stops the use of a service from a specific provider, and thus the user changes the purpose of use of the personal information in the privacy policy. In addition, a provider may change the privacy policy. For example, the provider may restrict use of the personal information in order to enhance the security.
The literatures as described above are silent to a technique that allows a change of the privacy policy to be reflected in all the providers that share thereamong the user's personal information. On the other hand, unless the change of the policy information is reflected in all the providers, handling of the personal information without the consent of the user may arise, which is improper from the view point of the protection of personal information. In addition, even if the change of privacy policy itself is reflected, it may occur that handling of the personal information is permitted outside the range of user's consent, unless the privacy policy thus changed is consistent with the privacy policy that is defined heretofore.